UNO: how to focus a slide

It seems, like focusing slide pages is handled differently from everything else. If I manually click on "Slides" panel the current slide, an option "Edit → Copy" would get highlighted, so I know I can copy it. However, if I print property desktop.CurrentComponent.CurrentSelection, it would be empty (unless you have selected an object in slide before, which then would be there).

So, then, how do I programmatically select a slide in "Slides" panel, so I could copy it?